Reconsolidation theory proposes that retrieval can destabilize an existing memory trace, opening a time-dependent window during which that trace is amenable to modification. Support for the theory is largely drawn from nonhuman animal studies that use invasive pharmacological or electroconvulsive interventions to disrupt a putative postretrieval restabilization ("reconsolidation") process. In human reconsolidation studies, however, it is often claimed that postretrieval new learning can be used as a means of "updating" or "rewriting" existing memory traces. This proposal warrants close scrutiny because the ability to modify information stored in the memory system has profound theoretical, clinical, and ethical implications. The present study aimed to replicate and extend a prominent 3-day motor-sequence learning study [Walker MP, Brakefield T, Hobson JA, Stickgold R (2003) Nature 425(6958): 616-620] that is widely cited as a convincing demonstration of human reconsolidation. However, in four direct replication attempts (n = 64), we did not observe the critical impairment effect that has previously been taken to indicate disruption of an existing motor memory trace. In three additional conceptual replications (n = 48), we explored the broader validity of reconsolidation-updating theory by using a declarative recall task and sequences similar to phone numbers or computer passwords. Rather than inducing vulnerability to interference, memory retrieval appeared to aid the preservation of existing sequence knowledge relative to a no-retrieval control group. These findings suggest that memory retrieval followed by new learning does not reliably induce human memory updating via reconsolidation.reconsolidation | sequence learning | memory updating | forgetting | replication

Aim: The aim of our study is to evaluate the prevalence of dental caries and periodontal disease in betel quid chewers in relation to gender and to determine the treatment need and priorities in Betel quid chewers attending Baqai Dental College. Material and Method:A cross sectional study conducted among patients selected from the out patient department of Baqai Dental College Karachi. A total of 100 patients aged between 22 to 60 years participated in the study. Patients with consumption of minimum seven betel quid since at least 6 months were included. Informed consent was obtained before the study began and each patient completed a questionnaire. The purpose of which was to access and obtain the information about the betel quid habits. Patients were asked to proceed for an oral examination as soon as they had finished filling the questionnaire. Reliability and validity of data was analyzed by chi square test using SPSS 19.0 version.Result: A Total of 100 patients were examined in this survey. The total number of sound teeth in males was 443(84%) and total number of teeth with decay was 85(16%). The total number of sound teeth in females was 207(76%) and total number of teeth with decay was 65(24%).Female subjects showed 61% of pocket 4-5mm, mostly observed in lower right first molar. In males 4-5mm pocket was 80%, Bleeding on probing was 1% in females and 4% in males. Pocket greater than 6mm was 27% in females and 16% in males. Conclusion:The present study concluded that effect of dental caries in betel quid chewers is less. A high prevalence rate of periodontal disease was found in betel quid chewers.Keywords: caries and betel quid chewers, Periodontal disease and betel quid chewers, Prevalence of betel quid chewing, Betel quid chewers and adults

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